In micro- and nanoengineering, hot embossing is used for transfer of a microscale or nanoscale pattern into a polymer layer. Here a flat substrate is first coated with a polymer and then is brought into contact with a prestructured die. Then the polymer is heated to liquefy it. The die is then pressed into the liquid polymer layer at a defined pressure. It is especially important to apply an embossing pressure which is as uniform as possible over the entire surface of the substrate. Then the polymer layer is molded by the die at a predefined temperature and cooled to room temperature.
Hot embossing is used among others for producing micro-optical structures, microfluidic components and magnetic data media.
Compared to photolithographic methods, the throughput for the above described hot embossing method is lower due to the thermal processes. For use of the hot embossing method in industrial mass production, for example production of hard disks or display screens, there would therefore be a demand for optimized throughput times. The maximum throughput time results from the sum of pumping-out time, heat-up time, embossing time, cooling time, molding time and ventilation time.
Different approaches such as shortening of thermal cycles, for example by use of polymers with low glass transition temperature, or the external cooling of the substrate after the embossing process have not shown the desired effects or have entailed other disadvantages. Thus, for example with partial heating of the embossing system due to different expansions of the individual components a distortion could be observed in the structure transition.